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A two dimensional Euler-Lagrangian model of wood gasification in a charcoal bed-Part II： Parameter influence and comparison

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Particuology 2017年第6期15卷 22-30页

作者： Stephan Gerber michael Oevermann Freie Universitat Berlin Arnimallee 6 14195 Berlin Germany Chalmers University of Technology Department of Applied Mechanics Division of Combustion Gothenburg Sweden

A Euler-Lagrangian simulation was employed for a comprehensive parameter study of wood gasification in a fluidized charcoal bed. The parameters that were varied include the initial bed temperature, fuel mass flow rate, inert tar fraction, and kinetic energy losses caused by particle-particle and particle-wall colli- sions. The results of each parameter variation are compared with a base scenario, previously described in detail in Part I of this study （Gerber ＆ Oevermann, 2014）. The results are interpreted by comparing the reactor outlet temperature, averaged particle temperature, overall wood mass, overall charcoal mass, concentrations of several gaseous species, and axial barycenter data for particles obtained with differ- ent sets of parameters. The inert tar fraction and fuel mass flow rate are the most sensitive parameter, while the particle-particle and particle-wall contact parameters have only a small impact on the results. Increasing the reactive tar components by 19% almost doubled the amount of reactive tars at the reac- tor outlet, while decreasing the restitution coefficients of the particle collisions by 0.2 results in higher overall gas production but almost no change in bed height. Herein, our numerical results are discussed in detail while assessing the model restrictions.

关键词： Wood gasification simulation Gas-solid flow Discrete element method Pyrolysis Gasification Charcoal

Euler-Lagrange/DEM simulation of wood gasification in a bubbling fluidized bed reactor

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Particuology 2009年第4期7卷 307-316页

作者： michael Oevermann Stephan Gerber Frank Behrendt Berlin Institute of Technology School of Process Sciences and EngineeringDepartment of Energy Engineering Fasanenstr.8910623 BerlinGermany

We present an Euler-Lagrange method for the simulation of wood gasification in a bubbling fluidized bed. The gas phase is modeled as a continuum using the 2D Navier-Stokes equations and the solid phase is modeled by a Discrete Element Method （DEM） using a soft-sphere approach for the particle collision dynamic. Turbulence is included via a Large-Eddy approach using the Smagorinsky sub-grid model. The model takes into account detailed gas phase chemistry, zero-dimensional modeling of the pyrolysis and gasification of each individual particle, particle shrinkage, and heat and mass transfer between the gas phase and the particulate phase. We investigate the influence of wood feeding rate and compare exhaust gas compositions and temperature results obtained with the model against experimental data of a laboratory scale bubbling fiuidized bed reactor.

关键词： Euler-Lagrange simulation Discrete element method (DEM) Dense fluidized bed Biomass gasification

A novel method of quantifying the coating progress in a three-dimensional prismatic spouted bed

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Particuology 2019年第1期17卷 137-145页

作者： Swantje Pietscha Finn Ole Poppinga Stefan Heinrich michael Müller michael Schonherr Frank Kleine Jager Hamburg University of Technology Institute of Solids Process Engineering and Particle TechnologyDenickestraβe 1521073 HamburgGermany BASF SE RCP/TT67056 LudwigshafenGermany

An optical method of experimentally quantifying the coating progress in a laboratory prismatic spouted bed is presented. Microcrystalline cellulose particles with size dp = 0.57 mm are used as core material. Waterborne coating suspensions with methylene blue as a dye are used and sprayed via a two-fluid nozzle in bottom-spray configuration. A high-speed camera with a color filter is positioned in front of the observation window of the three-dimensional plant and records the flow pattern in the process chamber with a certain frequency. With increasing surface coverage, the particles become bluer and darker. The change in brightness is detected by digital image analysis. In the implemented algorithm, the spherical particles are detected, cut from the background and normalized regarding their lighting and area. The detection of coated pixels on the single particles allows the calculation of the coating fraction and coating uniformity after a Kalman filter has been applied to reduce noise. It is shown that the method can be used to determine the time needed to reach the maximum blue value indicating a complete coating of the particle bed. Besides the minimum coating duration, information on the spraying performance (e.g., the time point of a possibly occurring blockage of the nozzle) can be obtained from the data. Two exemplary experiments are presented, showing a connection of the slope of the coating fraction and the uniformity of the coating of the particles in the apparatus that results in the recommendation of a slow liquid injection for obtaining consistent coating layers as desired in many applications.

关键词： Spouted bed Particle coating Granulation Digital image analysis

3D particle tracking velocimetry for the determination of temporally resolved particle trajectories within laser powder bed fusion of metals

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International Journal of Extreme Manufacturing 2019年第3期1卷 96-105页

作者： Eric Eschner Tobias Staudt michael Schmidt Institute of Photonic Technologies Friedrich-Alexander-Universität Erlangen-NürnbergKonrad-Zuse-Str.3/5D-91052ErlangenGermany Graduate School in Advanced Optical Technologies Friedrich-Alexander-Universität Erlangen-NürnbergPaul-Gordan-Str.6D-91052ErlangenGermany

Within this work,we present a system for the measurement of the three-dimensional(3D)trajectories of spatters and entrained particles during laser powder bed fusion(L-PBF)of *** is comprised of two ultrahigh-speed cameras and a reconstruction task specific processing reconstruction *** system enables an automated determination of 3D measures from the trajectories of a large number of tracked *** evolving from an underdetermined geometrical situation induced by a two-camera setup is resolved within the tracking using a priori knowledge of L-PBF of *** processing steps were optimized to run on a graphics processing unit to allow the processing of large amounts of data within an appropriate time *** overall approach was validated by a comparison of the measurement results to synthetic images with a known 3D ground truth.

关键词： powder bed fusion laser image processing additive manufacturing high-speed imaging 3D particle velocimetry

Particle behavior in a turbulent pipe flow with a flat bed

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Particuology 2023年第10期81卷 58-72页

作者： Min Liu Yanlin Zhao Yudong Yan michael Fairweather Jun Yao International Joint Laboratory on Clean Energy Science and Technology Beijing Key Laboratory of Process Fluid Filtration and SeparationCollege of Mechanical and Transportation EngineeringChina University of Petroleum-BeijingBeijing102249China School of Chemical and Process Engineering University of LeedsLeedsLS29JTUK

Particle behavior in a turbulent flow in a circular pipe with a bed height h=0.5r is studied at reb=40,000 and for two sizes of particles(5μm and 50μm)using large eddy simulation,one-way coupled with a Lagrangian particle tracking *** secondary flows are found within the pipe,with the curved upper wall affecting the secondary flow formation giving rise to a pair of large upper vortices above two smaller vortices close to the pipe *** behavior of the two sizes of particle is found to be quite *** 50μm particles deposit forming irregular elongated particle streaks close to the pipe floor,particularly at the center of the flow and the pipe corners due to the impact of the secondary *** deposition and resuspension rate of the 5μm particles is high near the center of the floor and at the pipe corners,while values for the 50μm particles are greatest near the *** the curved upper wall of the pipe,the deposition rate of the 5μm particles increases in moving from the wall center to the corners,and is greater than that for the larger particles due to the effects of the secondary *** maximum resuspension rate of the smaller particles occurs above the pipe corners,with the 50μm particles showing their highest resuspension rate above and at the corners of the pipe.

关键词： Sedimentary duct Secondaryflow Particle behavior Large eddy simulation

Experimental study and modeling of particle drying in a continuously-operated horizontal fluidized bed

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Particuology 2017年第5期15卷 134-146页

作者： Kaicheng Chen Philipp Bachmann Andreas Buck michael Jacob Evangelos Tsotsas Thermal Process Engineering Otto-von-Guericke-University Universityatsplatz 239106 MagdeburgGermany Glatt Ingenieurtechnik GmbH Nordstrasse 12 99427 Weimar Germany

Multistage fluidized beds are frequently used for product drying in industry. One advantage of these fluidized beds is that they can achieve a high throughput, when operated continuously. In this study, γ- A1203 particles were dried in a pilot-scale horizontal fluidized bed, without considering any comminution effects. For each experiment, the particle moisture content distribution and residence time distribution were determined. To take into account particle back mixing in our experiments, a one-dimensional pop- ulation balance model that considers particle residence time was introduced into a fluidized bed-drying model. Experimental particle residence time distributions were reproduced using a tank-in-series model. Subsequently, the moisture content distribution was implemented, as a second dimension to the popu- lation balance in this model. These two-dimensional simulations were able to describe the experimental data, especially the spread in the residual particle moisture distribution, much more accurately than one-dimensional simulations. Using this novel two-dimensional model, the effects of different operating parameters （process gas temperature, solid feed rate, superficial air velocity） on the particle moisture content distribution were systematically studied.

关键词： Continuous dryingHorizontal fluidized bed residence time distribution Moisture content distributionPopulation balance

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沁水盆地南部煤层气勘探成果与地质分析

天然气工业 2001年第4期21卷 35-38页

作者：樊生利中联煤层气有限责任公司

沁水盆地南部地区已累计投入 40口井的勘探工作量 ,并取得了重大的勘探成果 ,证实该区为煤层气高渗富集区。从含煤性、含气性、可采性等方面对该区进行了全面分析 ,得出以下认识 :煤层厚度较大 ,分布稳定 ;煤变质程度高 ,煤的吸附能力... 详细信息

沁水盆地南部地区已累计投入 40口井的勘探工作量 ,并取得了重大的勘探成果 ,证实该区为煤层气高渗富集区。从含煤性、含气性、可采性等方面对该区进行了全面分析 ,得出以下认识 :煤层厚度较大 ,分布稳定 ;煤变质程度高 ,煤的吸附能力强 ,含气量高 ,含气饱和度也较高 ;煤体结构、煤岩类型和煤质好 ,煤层割理较发育 ,渗透性较好 ,适合于压裂改造 ;区域构造稳定 ,煤系及上覆连续地层保存较好 ,后期改造、断裂不严重 ,构造较简单 ,煤层气赋存和保存条件好 ;煤层埋藏较浅 ;水文地质条件比较有利。综合评价该区煤层气具有良好的可采性 ,可以作为我国第一个煤层气滚动勘探开发区块。

关键词：沁水盆地煤成气勘探成果勘探评价滚动开发地质分析

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影响煤层气井产量的因素分析

天然气工业 2004年第4期24卷 62-64页

作者：娄剑青中联煤层气有限责任公司

煤层甲烷在煤储层中的储集及渗流与常规天然气大不相同 ,其影响因素多样而复杂。影响煤层气产量的主要因素是煤层渗透率、煤层厚度及含气量。大量煤层气井生产实践证明 ,含气量是影响产量的物质基础 ,而渗透率是影响产量大小的控制性因... 详细信息

煤层甲烷在煤储层中的储集及渗流与常规天然气大不相同 ,其影响因素多样而复杂。影响煤层气产量的主要因素是煤层渗透率、煤层厚度及含气量。大量煤层气井生产实践证明 ,含气量是影响产量的物质基础 ,而渗透率是影响产量大小的控制性因素。煤层含气量与煤层厚度及埋深一般有正相关关系 ,而渗透率一般随埋深增加而减小。用产气潜能与产气能力将更全面地反映含气量及渗透率对煤层气井产量的影响。把含气量引入达西流产量公式也许能更真实地反映甲烷气体在煤储层中流动产出的特征。

关键词：煤层气井产量地层厚度含气量渗透率产能评价甲烷

Synthesis of aluminum nitride in a coke – calcium reduction bed using nitrogen in air

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International Journal of Minerals,Metallurgy and Materials 2015年第9期22卷 972-976页

作者： Ehsan Noorizadeh Dehkordi H.r.Samim Banihashemi r.Naghizadeh H.r.rezaie M.Goodarzi School of Metallurgy & Materials Engineering Iran University of Science & Technology

An experimental study on the heating of a mixture of aluminum and lithium hydroxide （LiOH） powders in a reductive bed under air atmosphere is reported. The formation of aluminum nitride （A1N） during this process was the focus of this study. The formation of A1N was achieved using LiOH as an additive and heating the sample in a resistance furnace in a specially designed double crucible within a bed of a mixture of coke and filamentous calcium. The temperature range of the reaction was between 700℃ and 1100℃. The optimum temperature of 1100℃ and the optimum LiOH amount （Swt%） required to achieve maximum yield were determined by powder X-ray diffraction （XrD） analysis. Scanning electron microscopy （SEM） micrographs clearly indicated the transformation of grain structures from rods （700℃） to cauliflower shapes （1100℃）.

关键词： aluminum nitride synthesis nitridation lithium hydroxide reaction temperature